1. Field of the Invention
The present invention relates to a system for measuring torque in a rotating shaft by means of generating and processing optically derived electrical signals which are a function of the torsional deflection of the shaft. The present invention further relates to a system for measuring angular velocity, power output and efficiency of a rotating shaft by means of generating and processing optically derived electrical signals which are functions of the angular velocity and torsional deflection of the shaft.
2. Description of the Prior Art
Devices for measuring torque through electronic conversion of optical signals generally are well known in the prior art. Attention is called to U.S. Pat. Nos. 3,196,675 (Buchele, et al, issued July 27, 1965); 3,495,452 (Johnson, Jr., et al, issued Feb. 17, 1970); 3,897,766 (Pratt, Jr., et al, issued Aug. 5, 1975); 3,940,979 (Ward, et al, issued Mar. 2, 1976); 3,111,028 (Lebow, issued Nov. 19, 1963); 3,950,986 (Parkinson, issued Apr. 20, 1976); 3,625,055 (Lafourcade, issued Dec. 7, 1971); 3,596,100 (Hollick, issued July 27, 1971); 3,604,255 (Bart, issued Sept. 14, 1971); 3,545,265 (McIlraith, et al, issued Dec. 8, 1970); 3,960,012 (Ingram, issued June 1, 1976) and 4,166,383 (Lapeyre, issued Sept. 4, 1979).
The prior art optical torque meters--Johnson, Jr., et al, Pratt, Jr., et al, and Buchele, et al--utilize a deflection principle in which light is transmitted from a light source and reflected from a shaft onto an optoelectronic sensor for subsequent signal processing into convenient form. This reflection method is hampered by errors produced by inconsistent turn-on times of the optoelectronic sensor caused by scattered light which results in decreased intensity of reflection.
The prior art optical torque meters that utilize a direct beam pick up similar to that used in the present invention generally are all mechanically intricate and involve complex shaft attachments such as slotted rotating disks (Ward, et al), toothed flanges (Lebow), toothed wheels (Parkinson), double shafts with a rotating disk on one of them (Lafourcade), and light polarizing screens (Hollick). These devices are expensive and time-consuming to machine, require specific technical knowledge to install and service, cannot be placed on a shaft different from that on which it was initially placed without machining alterations, utilize complex curcuitry in which conversion of analog signals to digital readouts is necessary, and suffer a scattered light problem similar to the deflective torquemeters mentioned above.
Systems for measuring power, angular velocity and shaft efficiency generally are also known. Such devices use a variety of relatively complex methods--e.g. a proximity pick-up located adjacent to gears mounted on the shaft and generating alternating current waves (Bart), magnetic sensors (McIlraith, et al), and assemblies to separately generate signals proportional to torque and angular velocity (Ingram). In addition to the necessity of analog to digital signal conversion and the relative complexity of the measurement process, none of the prior art devices use optical signal transmission as does the present invention.